__in filter modifier ignore None value

Describe the bug
I have a model Player with optional ForeignKey field team. I want to get all the players who are on team 1 or not on any team. But if I use a filter team_id__in=[team1.id, None], it returns only those players who are in the team 1

To Reproduce

from tortoise import Tortoise, fields, run_async
from tortoise.exceptions import NoValuesFetched
from tortoise.models import Model


class Team(Model):
    id = fields.IntField(pk=True)
    players: fields.ReverseRelation["Player"]


class Player(Model):
    id = fields.IntField(pk=True)
    team: fields.ForeignKeyRelation[Team] = fields.ForeignKeyField(
        "models.Team", related_name="players", null=True, default=None
    )
    nick = fields.CharField(max_length=10)

    def __repr__(self):
        return f"Player(nick={self.nick})"


async def run():
    await Tortoise.init(db_url="sqlite://:memory:", modules={"models": ["__main__"]})
    await Tortoise.generate_schemas()

    team1 = await Team.create(id=1)
    team2 = await Team.create(id=2)

    p1 = await Player.create(team=team1, nick="p1")
    p2 = await Player.create(team=team1, nick="p2")
    p3 = await Player.create(team=team1, nick="p3")
    p4 = await Player.create(team=team1, nick="p4")
    p5 = await Player.create(team=team2, nick="p5")
    p6 = await Player.create(team=team2, nick="p6")
    p7 = await Player.create(team=team2, nick="p7")
    p8 = await Player.create(nick="p8")
    p9 = await Player.create(nick="p9")

    res = await Player.filter(team_id__in=[team1.id, None])
    print(res)  # => [Player(nick=p1), Player(nick=p2), Player(nick=p3), Player(nick=p4)]
    print(len(res))  # => 4


if __name__ == "__main__":
    run_async(run())

Expected behavior
Query team_id__in=[team1.id, None] returns all the players who are on team 1 or not on any team.

res = await Player.filter(team_id__in=[team1.id, None])
print(res)  # => [Player(nick=p1), Player(nick=p2), Player(nick=p3), Player(nick=p4), Player(nick=p8), Player(nick=p9)]
print(len(res))  # => 6

I know that i can use something like this

from tortoise.query_utils import Q
res = await Player.filter(Q(team_id__isnull=True) | Q(team_id=team1.id))

and i'm not sure if this is a bug or not, but it would be great if the __in modifier worked the same way as in in Python

Start with the Player.filter(team_id__in=[team1.id, None]) entry point and trace how the __in modifier is translated for the SQLite example. Compare the generated query behavior with the Q(team_id__isnull=True) | Q(team_id=team1.id) alternative. Done means the example returns all six matching players, including those with no team.